M Munakata

Harvard Medical School, Boston, Massachusetts, United States

Are you M Munakata?

Claim your profile

Publications (24)37.3 Total impact

  • Mamoru Munakata, Masaharu Hatakeyama, Yuichi Ono
    Asian cardiovascular & thoracic annals 04/2013; 21(2):245-6.
  • Mamoru Munakata, Masaharu Hatakeyama, Yuichi Ono
    [Show abstract] [Hide abstract]
    ABSTRACT: A 74-year-old man underwent aortic valve replacement due to aortic regurgitation after two months of medication for congestive heart failure. At surgery, the cause of the aortic regurgitation appeared to be dehiscence of an aortic valve commissure. Dehiscence was closed with mattress sutures from outside of the sinus. Dehiscence of an aortic valve commissure is rare and difficult to be diagnosed preoperatively, and we carefully repaired it, and the patient had a good recovery.
    Annals of thoracic and cardiovascular surgery : official journal of the Association of Thoracic and Cardiovascular Surgeons of Asia. 12/2011;
  • Mamoru Munakata, Hiroyuki Itaya, Kozo Fukui, Yuichi Ono
    The Journal of thoracic and cardiovascular surgery 04/2007; 133(3):798-9. · 3.41 Impact Factor
  • Source
    Mamoru Munakata, Hiroyuki Itaya, Yuichi Ono
    [Show abstract] [Hide abstract]
    ABSTRACT: A 46-year-old male had a cardiac stab injury resulting in cardiac tamponade as a result of a suicide attempt using a bodkin, a sharply pointed instrument for making holes. The patient was transferred to our hospital about 12 hours after the injury. Pericardiotomy at the emergency operation revealed the penetration of the right ventricle and the hole was repaired following removal of the bodkin. Postoperative course was uneventful.
    Annals of thoracic and cardiovascular surgery: official journal of the Association of Thoracic and Cardiovascular Surgeons of Asia 11/2006; 12(5):365-7. · 0.47 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A 64-year-old man underwent aortic valve replacement for aortic regurgitation. The aortic valve was perforated in the noncoronary cusp. Pathological findings showed that the perforation probably occurred due to infective endocarditis. However, the patient had no obvious inflammatory signs preoperatively, to suggest latent infective endocarditis.
    The Japanese Journal of Thoracic and Cardiovascular Surgery 03/2006; 54(2):67-9.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Severe circulatory failure after cardiovascular surgery is occasionally difficult to treat and the mortality risk is high. Systemic inflammatory response syndrome (SIRS) is one of the complications resulting in circulatory failure and, continuous hemodiafiltration (CHDF) seems to be a potentially effective treatment to improve the critical condition by removing proinflammatory cytokines. We present two recent cases of SIRS with critical circulatory failure which were successfully treated by CHDF after operation for thoracic aortic dissection.
    Annals of thoracic and cardiovascular surgery: official journal of the Association of Thoracic and Cardiovascular Surgeons of Asia 09/2005; 11(4):277-80. · 0.47 Impact Factor
  • The Annals of thoracic surgery 02/2005; 79(1):355. · 3.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Mediastinal irradiation has been reported to induce cardiac disease such as pericarditis, valvular dysfunction, conduction abnormalities, accelerated arteriosclerosis of the coronary arteries, and also calcifications of the ascending aorta. We herein describe a case of radiotherapy-induced porcelain aorta and aortic valve disease and their surgical treatment. The patient was diagnosed with myasthenia gravis (MG) in 1965 (Osserman's type II), and mediastinal irradiation was performed in 1970 for treatment of thymic tumor associated with MG. Thirty years after radiation therapy, complete atrioventricular block and aortic valve disease with severe calcification of the ascending aorta and aortic arch (porcelain aorta) were detected on echo cardiogram and cardiac catheterization. A permanent pacemaker was implanted via the left subclavian vein and aortic valve replacement was performed under extracorporeal circulation established by selective cerebral perfusion and balloon occlusion instead of aortic cross-clamping. As no risk factors of arteriosclerosis such as hypercholesterolemia, hyperglycemia and hypertension were apparent, we concluded that the aortic valve disease and porcelain aorta were primarily induced by radiotherapy.
    The Japanese Journal of Thoracic and Cardiovascular Surgery 08/2004; 52(7):349-52.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: pledget-supported suture. We did not use this method because of suspected infection and the severely damaged PA wall. The his- tologic findings also support our decision. However, the PA wall was extensively abnormal, and the suture line was disrupted. Resuturing incorporating the pulmonary valve annulus caused mild residual stenosis that could not be tolerated in the presence of severe right ventricular dysfunction. Pulmonary root replacement can be a method of choice in such patients. Therefore, we believe that a pulmonary allograft should also be made available whenever possible and should be implanted during the initial operation, if necessary. The last problem was the timing of the operation. Emergency intervention was required in most reported patients with aortopul- monary fistulae and in this patient also, although the history of the present illness was rather long, and his general condition was fair
    Journal of Thoracic and Cardiovascular Surgery 09/2003; 126(2):600-2. · 3.53 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A 27-year-old male whose diagnoses were aortic dissection (Stanford A), aortic regurgitation, annulo-aortic ectasia, and Marfan syndrome underwent modified Bentall operation using composite graft and total arch replacement. Modification of proximal suture without resection of aortic valve like intravalvular implantation might have resulted in good recovery without blood transfusion. Another 63-year-old male who suffered from spontaneous aortic rupture with aortic regurgitation also underwent modified Bentall operation in the similar manner as the first case with good result. Spontaneous aortic rupture reported here is a rare case, and operation is thought to be prerequisite for the patient who suffers from this disease to survive.
    Kyobu geka. The Japanese journal of thoracic surgery 12/2002; 55(12):1039-42.
  • [Show abstract] [Hide abstract]
    ABSTRACT: A family of 3 patients with Marfan syndrome was reported. All of them had surgical interventions in cardiovascular disorders such as DeBakey type I, III aortic dissection and thoracoabdominal aortic aneurysm. In 2 patients, multiple surgical treatments were performed for aneurysmal dilatation of the distal false lumen or another lesions of the treated aorta. Since cardiovascular lesions of Marfan syndrome are systemic and progressive, the postoperative long term follow-up, including systemic evaluation of the arterial system, is essential to detect the latent cardiovascular complications. Careful examining the family with Marfan syndrome is necessary to discover any cardiovascular abnormalities in these people early.
    Kyobu geka. The Japanese journal of thoracic surgery 08/2002; 55(8 Suppl):683-7.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Protein kinase C (PKC) activation during myocardial ischemia is thought to be cardioprotective. However, the mechanism of ischemia-induced PKC activation remains unclear. We hypothesized that ischemic PKC activation occurs through activation of phosphatidyl-inositol specific phospholipase C (PI-PLC) and protects the heart from ischemic injury. Isolated rabbit hearts were subjected to 20 minutes of normothermic ischemia and reperfusion. The PI-PLC inhibitor U73122 (0.5 micromol/L), its inactive analogue U73343 (0.5 micromol/L), or the PKC inhibitor chelerythrine (2 micromol/L) were given just before ischemia. Another group received U73122 plus the direct PKC activator phorbol 12-myristate-13-acetate (PMA, 10 pmol/L). Measurements included contractile function, intracellular calcium, PI-PLC activity, and translocation of PKC isoforms. PI-PLC activity increased during myocardial ischemia and was inhibited by U73122. PI-PLC inhibition prevented the ischemic translocation of PKC-alpha, PKC-epsilon, and PKC-eta, and impaired cardiac recovery and cytosolic calcium regulation without significant changes in energy metabolism. PMA restored both contractile function and PKC translocation pattern in U73122-treated hearts. Direct PKC inhibition with chelerythrine mimicked the effects of U73122. PI-PLC mediates PKC translocation during myocardial ischemia. Inhibition of PI-PLC or PKC activation, or both, during ischemia significantly impairs postischemic myocardial recovery.
    The Annals of Thoracic Surgery 05/2002; 73(4):1236-45. · 3.45 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Because of the decreased tolerance to ischemia and increased reperfusion injury in hypertrophied myocardium, myocardial hypertrophy is a well known risk factor for cardiac surgery. We have previously demonstrated in a left ventricular hypertrophy (LVH) model that a highly buffered cardioplegic solution (HBS) that provided glucose as a substrate and promoted anaerobic glycolysis during ischemia afforded superior myocardial protection when compared to standard formulations. And we reported the superiority of this cardioplegia in human cardiac surgery. In this study, 16 patients with aortic stenosis (AS) and LVH receiving HBS were reviewed and compared to another patient group with AS and LVH who received either cold blood cardioplegia (CBC; n=5) or glucose insulin potassium (GIK; n=6). Postoperative cardiac index was better in the HBS group than the other two groups with similar or lower catecholamine. CK-MB was lower in HBS group than GIK group, but this was not significant. Only one DC cardioversion was required in the HBS group, whereas 2 DC in the CBC group and total 7 DC in the GIK group. We found that histidine buffered cardioplegic solution provided comparable or better pump performance after surgery with relatively lower inotropic requirement, less DC cardioversion and homologous blood requirements for left ventricular hypertrophied heart associated with aortic stenosis.
    The Journal of cardiovascular surgery 03/2002; 43(1):37-41. · 1.51 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The cellular mechanisms of abnormal calcium regulation and excitation-contraction coupling in relation to glucose metabolism in the hypertrophied heart are not well understood. The present study evaluated the myocardial mechanics of 6-7-week-old pressure overload hypertrophied rabbit hearts in response to dobutamine by (1) serial echocardiograms in vivo and (2) isolated Langendorff perfusion. Cytosolic Ca2+([Ca2+]i) and sarcoplasmic reticulum Ca2+-ATPase (SERCA2) expression were measured by fluorescence spectroscopy and Western immunoblotting, respectively. The effect of glycolytic inhibition by 2-deoxy-D-glucose +/- pyruvate was also evaluated. Both systolic and diastolic [Ca2+]i tended to be higher and diastolic calcium removal (tauCa) significantly slower in the hypertrophied heart. The myocardial response to dobutamine was blunted and dobutamine insignificantly improved tauCa. The SERCA2 protein level was higher in early hypertrophy, but was significantly reduced by 6 weeks of age, with progressive contractile failure. Inhibition of glycolysis or SERCA2 caused an increase in [Ca2+]i as well as a slower tauCa. Pyruvate completely preserved myocardial function and [Ca2+]i handling during glycolytic inhibition. It was concluded that in this model of advanced pressure overload hypertrophy, contractile failure and inotrope insensitivity are associated with increased [Ca2+]i, slower tauCa and reduced sensitivity of the contractile proteins to Ca2+. These changes occur in association with downregulation of the SERCA2, probably caused by impaired glucose metabolism.
    Japanese Circulation Journal 01/2002; 65(12):1064-70.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Protein kinase C (PKC) activation impairs contractility in the normal heart but is protective during myocardial ischemia. We hypothesized that PKC remains activated post-ischemia and modulates myocardial excitation-contraction coupling during early reperfusion. Langendorff-perfused rabbit hearts where subjected to 25 min unmodified ischemia and 30 min reperfusion. Total PKC activity was measured, and the intracellular translocation pattern of PKC-alpha, -delta, -epsilon, and -eta assessed by immunohistochemistry and fractionated Western immunoblotting. The PKC-inhibitors chelerythrine and GF109203X were added during reperfusion and also given to non-ischemic hearts. Measurements included left ventricular function, intracellular calcium handling measured by Rhod-2 spectrofluorometry, myofibrillar calcium responsiveness in beating and tetanized hearts, and metabolic parameters. Total PKC activity was increased at end-ischemia and remained elevated after 30 min of reperfusion. The translocation pattern indicated PKC-epsilon as the main active isoform during reperfusion. Post-ischemic PKC inhibition affected mainly diastolic relaxation, with lesser effect on contractility. Both PKC inhibitors increased the Ca(2+) responsiveness of the myofilaments as indicated by a leftward shift of the calcium-to-force relationship and increased maximum calcium activated tetanic pressure. Diastolic Ca(2+) removal was delayed and the post-ischemic [Ca(2+)](i) overload further exacerbated. Depressed systolic function was associated with a lower amplitude of [Ca(2+)](i) transients. PKC is activated during ischemia and remains activated during early reperfusion. Inhibition of PKC activity post-ischemia impairs functional recovery, delays diastolic [Ca(2+)](i) removal, and increases Ca(2+) sensitivity of the contractile apparatus, resulting in impaired diastolic relaxation. Thus, post-ischemic PKC activity may serve to restore post-ischemic Ca(2+) homeostasis and attenuate contractile protein calcium sensitivity during the period of post-ischemic [Ca(2+)](i) overload.
    Cardiovascular Research 08/2001; 51(1):108-21. · 5.81 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Endotoxin (lipopolysaccharide, LPS) is a trigger of the systemic inflammatory response. We have previously found that vesnarinone and amrinone, when given before LPS, prevented cytokine production and LPS-related cardiac dysfunction. We tested the hypothesis that vesnarinone would improve intracellular Ca(2+) handling and calcium-activated contractile force after the onset of endotoxemia. Adult rabbits received a bolus injection of LPS or vehicle. Vesnarinone (3 mg/kg) was given intravenously 90 minutes later. Two hours after LPS administration, hearts were perfused in the isolated Langendorff mode. Peak left ventricular developed pressure, +/-dp/dt, oxygen consumption (MVO(2)), and ratexpressure product were evaluated in conjunction with fluorescent spectroscopic determinations of intracellular calcium concentrations (Ca(i)) and the rate of Ca(i) transient decline during diastole (tauCa). Peak left ventricular developed pressure and +/-dp/dt were significantly lower in the LPS group. These were completely restored by vesnarinone. There was significantly slower diastolic calcium removal (increased tauCa) in LPS hearts that was also corrected by vesnarinone; however, the cytosolic calcium overload characteristic of LPS hearts was only partially improved. Reduced mechanical inefficiency (the ratio of rate-pressure product to MVO(2)) and myofilament sensitivity to Ca(i) were also significantly improved by vesnarinone. Acute endotoxemia caused contractile protein calcium insensitivity, oxygen wastage, and abnormal calcium cycling. Vesnarinone, given in the rescue mode, normalized LPS-induced myocardial dysfunction and partially restored abnormal calcium cycling. Although the mechanisms responsible for these effects require further clarification, it appears that agents such as vesnarinone may be useful to treat inflammatory-induced myocardial dysfunction.
    Circulation 12/2000; 102(19 Suppl 3):III365-9. · 15.20 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Increasingly complex techniques of cardiac surgery often require prolonged myocardial ischemia. We previously reported a better myocardial preservation with histidine containing cardioplegia (HBS) in human open heart surgery. To see a safety margin of this cardioplegia for prolonged myocardial preservation, this study was retrospectively done. One hundred twenty-six patients received either intermittent multidose (20-30 minute) cold blood cardioplegia (CBC) plus topical cooling (aotric cross clamp time (ACC) < 120 minutes, n = 63) or HBS (n = 63). HBS group was divided into two groups with either short ACC (< or = 120 minutes, HBS-S, n = 46) or long ACC (> 120 minutes, HBS-L, n = 17). Cardiac index (C.I.) and dopamin/dobutamine requirement were measured 3, 6, and 12 hours post-bypass. Incidence of homologous blood transfusion was also studied. There was two deaths due to LOS in HBS-S group; four patients in HBS group required 5 DC cardioversion, whereas six patients required a total of 12 DC cardioversion in CBC group. Functional recovery were significantly better with significantly lower inotropic requirements in HBS-S group than CBC group and HBS-L group. Although preoperative ejection fraction and C.I. were significantly lower in HBS-L group, post-operative cardiac function and inotropic requirements in HBS-L was comparable to that seen in CBC group. We conclude that the highly buffered histidine crystalloid cardioplegia solution provides effective myocardial preservation with a wider safety margin for prolonged myocardial preservation in open heart surgery.
    Kyobu geka. The Japanese journal of thoracic surgery 07/1999; 52(6):467-70.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Preoperative evaluation of the both right ventricular (RV) systolic and diastolic function using the pulsed Doppler echocardiogram were examined for 46 patients scheduled for the pulmonary resection of the pulmonary tumorous lesions. The parameters which included the RV inflow pattern at the tricuspid orifice and the RV ejection flow pattern at the RV outflow tract were obtained by the pulsed Doppler echocardiogram. Following results were obtained. 1) The RV afterload shown by the parameters of the acceleration time (AT, time beginning of RV ejection to peak velocity) were higher in the aged patients, the low FEV 1% populations, and the patients having the deteriorated left ventricular contraction. 2) The RV diastolic dysfunction were present preoperatively in aged patients over the 60 years old. This phenomenon was characterized by a high degree of atrial contraction and an increased ratio of the peak velocity in atrial contraction phase to that in early rapid filling phase (A/E). When we evaluate the RV inflow and ejection Doppler flow patterns after the major lung resection, these findings must be considerable thing.
    Kyobu geka. The Japanese journal of thoracic surgery 08/1997; 50(7):535-9.
  • [Show abstract] [Hide abstract]
    ABSTRACT: A case was 6-year-old female diagnosed as the cor triatriatum. The magnetic resonance imaging synchronized at R wave on the electrocardiogram was performed in order to see the abnormal septum in the left atrium. In the horizontal view, the abnormal septum that divides the left atrium into the accessory left atrial chamber and the true left atrium, was well visualized. This septum lied on the vertical portion. Operation was carried out with the approach through the accessory chamber and the fibromuscular membrane were excised. Preoperative imaging of the MRI was useful and helpful for us to reach to a decision of the surgical approach in this patient.
    Kyobu geka. The Japanese journal of thoracic surgery 11/1996; 49(11):921-3.
  • [Show abstract] [Hide abstract]
    ABSTRACT: Topical cooling with iced slush has been applied as a conventional myocardial preservation in open heart surgery. However, there might be several disadvantages due to topical cooling with iced slush which melted to be liquid, because of membrane integrity decreased during ischemia. To understand more detailed mechanism of deterioration for myocardium by immersion in some liquid during ischemia, we subjected isolated crystalloid perfused rabbit hearts to a 30 minute of ischemia with immersion in Krebs-Henseleit (K-H) solution (I), K-H+hexamethlyamiloride which was Na+/H+ channel blocker (II) and histidine containing cardioplegia (HBS) designed to accelerate anaerobic glycolysis by a proton buffering (III), followed by a 30 minute of reperfusion. These groups were compared to the hearts hanging in air during ischemia (control). Phosphocreatine (PCr), ATP and intracellular pH were measured by 31 PNMR in group I, II, III. Developed pressure (Dev P) and diastolic pressure (EDP) with a intracavitary balloon were also evaluated with monitoring of 2 mmHg diastolic contracture during ischemia. Dev P declined to 46%, 54% of preischemic value in group I and group II, respectively, although % recovery of control heart was 74% after ischemia-reperfusion process. Diastolic function was severely deteriorated in group I and II, as compared to control heart. ATP and intracellular pH showed a similar decline as PCr in group I and II which was not seen in group III during ischemia. HBS prevented the deterioration of PCr, ATP and intracellular pH during ischemia along with excellent recovery of myocardial function. We therefore conclude that 1) significant deterioration of myocardium occurs with ischemia if the heart preserved in Krebs-Heseleit solution and the mechanism of injury by immersion in liquid on the heart appears to be due to proton accumulation caused by intracellular acidification and loss of high energy phosphate.
    [Zasshi] [Journal]. Nihon Kyōbu Geka Gakkai 10/1996; 44(9):1691-7.